Extruders are often used in the preparation of various food products and especially in the preparation of ready-to-eat (“RTE”) cereals such as puffed. Extruders, especially cooker extruders, are desirable because a single machine can produce large quantities of a cooked cereal dough in a short period of time. Such cooker extruders can be used to prepare cooked dough extrudates which can thereafter be formed into individual cereal or snack pieces, with the formation of such pieces possibly involving puffing the pieces to form finished puffed RTE cereals. In another variation that is increasingly popular, the conditions of the extruder and the cooked cereal dough are such that the dough puffs immediately upon being extruded and is cut into individual puffed pieces at the die head. Such a process is referred to generally as “direct expansion.”
While the preparation of a puffed or “direct expanded” extrudate is desirable, it may be desirable to produce a variety of products having different colors, flavors, or similar additives. For example, RTE cereal blends that comprise a mixture of differently shaped pieces are desirable, with each shape having a distinctive color and/or flavor.
In current practice, in order to produce an RTE cereal blend of distinctive colors, shapes or flavors, a sequence of individual color/flavor runs are made. The product from each run is collected and subsequently admixed to form the blend. For instance for a direct expanded product, a first colored cooked cereal dough is prepared by adding color to the starting material or by injecting a color into the dough upstream of the dieface. The colored dough is directly expanded through a shaped dieface and face cut as it expands to form individual pieces. To prepare, for instance, a second color and shape, the first color injection is discontinued and a second different color material is injected into the cooked cereal dough. To prepare a second shape, the first die head is removed and substituted with a die head having the desired second shape.
While effective, one problem with this conventional practice resides in the generation of unusable scrap material during the color addition transition as the new color is admixed with the residual amounts of the prior color. Still more scrap is generated as the extruder comes up to steady state conditions after the second color run is started. A second problem is that the various colored pieces must be collected in large batches to be admixed at a later time to form the blended RTE cereal. The properties (e.g., plasticity, temperature, moisture content, starch conditions, frangibility, etc.) of the finished pieces may deteriorate over the storage period. A third problem relates to the broken pieces, dust and/or cereal fines created by the admixing step.
As shown by the continuing market success, the methods and apparatus of U.S. Pat. No. 5,919,509 were a major advancement in the art to overcome the problems previously faced in the preparation of various food products. However, there is continuing need to provide food products having novelty in form to maintain or enhance market share.
It would thus be desirable to be able to provide a multiplicity of streams of mixed, non-homogenous cooked cereal dough from a single extruder, with each of the streams having a distinct color, flavor and/or similar additive.